KR20090011055A - Fabric from radioactive ray shield - Google Patents

Abstract

Radiation shielding fiber is provided to achieve operator's safety by previously preventing operators from being exposed to radiation during operation period of an atomic power facility. Radiation shielding fiber includes a first and a second radiation shielding layers(1), a first and a second impermeable resin layers(3) and a neutron shielding layer(2). A coating layer is formed on surfaces of the first and the second radiation shielding layers. The coating layer is made of polyurethane resin. The first and the second impermeable resin layers are made of polyolefin resin or polyolefin containing inorganic material. The neuron shielding layer is a sheet of a gel shape. The sheet is formed through mixing/extruding/foaming process of thermoplastic polyolefin with 100 weight part, foam agent with 0.1 to 10 weight parts, and foam making and bridge making agents with 0.5 to 50 weight parts. The sheet is sealed between impermeable resin layers. At least one element of gadolinium boron and lithium is dispersed in molten paraffin with 100 weight part. The porosity of the sheet is 30 to 90 %.

Description

Radiation shielding fiber {Fabric from radioactive ray shield}

Places where there is a lot of radiation, or where there is a lot of radiation, for example, those working in the radiation zones of nuclear power plants or in industrial sites handling radiation transmission test equipment are always at risk of exposure to radiation.

It is well known that radiation, such as x-rays and gamma rays, causes many serious diseases and disorders, including carcinogenesis, genetic disorders, and cataracts. Accordingly, in 1934, the International Commission on Radiation Protection was launched to limit the use of radiation (0.2 R / day), and in 1977 the International Recommendation on Radiation Protection (ICRP-26) was adopted, followed by X-ray diagnosis, treatment and nuclear Guidelines for reducing the exposure of patients, workers and carers to medicine have been published, and countries have enacted laws on the use of radiation.

As such, exposure to radiation is very harmful to the human body, so it should be made as limited as possible. However, people who directly or indirectly deal with radiation, such as radiologists, doctors, and nuclear power personnel in hospitals, may be exposed to radiation continuously because of their work characteristics. Should be

Therefore, in order to protect the workforce when working in places with high radiation such as repair or inspection of nuclear power plants, radiation shielding suits are worn to protect from the danger of exposure.

The present invention relates to a shield member for the production of such radiation shielding clothing.

As a method for shielding the radiation exposure, it is common to wear a sheet-like gown formed by dispersing lead components in a rubber and then extruding them. However, gowns made in this way are effective for radiation shielding, but are very heavy, such as 5-10 kg, and have a poor fit.

At this time, the thickness of the lead plate should be thick enough to block the radiation, but if it is too thick, the shielding clothing is heavy, making it difficult to wear and making the operation very uncomfortable.

The working environment in which radiation is generated is not always constant. In other words, if you are working near a nuclear reactor or in a workshop that handles low-radiation wastes, wear lighter clothing that is lighter and less disruptive than working with thick lead shields. It is preferable.

However, until now, the only option was to use thick lead shields that block radiation, or to use protective clothing that blocks dust from the radiation.

That is, there was no convenient shielding suit that shielded only a small degree of radiation in the working environment with low radiation generation and increased work activity.

As a lighter shielding suit, US Patent No. 3,194,239 discloses a method of manufacturing radiation absorbing fibers using an alloy wire for radiation absorption, but this has a problem of poor flexibility and radiation shielding properties.

It is an object of the present invention to provide a convenient shielding suit which can shield an appropriate amount of radiation without the use of lead that is harmful to the human body, and is easy to work.

The present invention is to solve the above problem, to effectively block the radiation by laminating a neutron shielding layer between the radiation shielding layers. The neutron shielding layer prepares a sheet in which pores are formed by using a polyolefin resin with a blowing agent, stretches the sheet to form reticulated pores, and injects / impregnates molten paraffin in which metal nanoparticles are dispersed, and between impermeable resin layers. It is formed by sealing. The radiation shielding layer forms a coating layer on the surface of the fabric, and the coating layer uniformly disperses barium sulfate and an organic iodine-based radiocontrast compound in powder form. In the present invention, the radiation shielding member may increase the selection width by adjusting the thickness of the neutron shielding layer according to the radiation neutron energy intensity.

Specifically,

The present invention is a first radiation shielding layer (1); The first impermeable resin layer 3; Neutron shielding layer 2; Second impermeable resin layer 3; And a second radiation shielding layer 1,

The first and second radiation shielding layer is formed with a coating layer made of polyurethane resin on the surface of the fabric, the barium sulfate and the organic iodine-based radiographic compound is uniformly dispersed in powder form inside the coating layer,

The first and second impermeable resin layers are composed of a polyolefin resin or a polyolefin resin containing an inorganic material,

The neutron shielding layer is mixed with 0.1 to 10 parts by weight of a blowing agent, 0.5 to 50 parts by weight of a foaming aid and a crosslinking aid with respect to 100 parts by weight of thermoplastic polyolefin, and foamed after extrusion to prepare a sheet, and the sheet is stretched to form network pores. Thereafter, at least one or more elements of gadolinium, boron, and lithium having a particle size of 1 to 10 parts by weight are dispersed in 100 parts by weight of molten paraffin, injected into the sheet, and obtained by sealing between the impermeable resin layers, The sheet is characterized in that the porosity is 30 to 90%.

In addition, in the neutron shielding layer of the present invention, the impermeable resin layer is characterized in that the polyolefin resin containing at least one element of gadolinium, boron, lithium having an average particle size of less than 10㎛ diameter.

Radiation exposure of equipment workers and maintenance workers by radiation workers during operation of nuclear power plants or nuclear facilities can be prevented in advance, and safety hazards can be secured for nuclear workers by reducing hazards to health risks.

Detailed embodiments of the invention are disclosed herein. It should be understood, however, that the disclosed embodiments may be practiced in various forms only as illustrations of the invention. Accordingly, the detailed description disclosed herein should not be construed as limiting, but merely as a basis for teaching those skilled in the art to the basis of the claims and how to make and / or use the invention.

In the radiation shielding layer 1 according to the present invention, a coating layer made of a polyurethane resin is formed on a fabric surface, and barium sulfate (BaSO 4) and an organic iodine-based radiocontrast compound are uniformly dispersed in a powder form inside the coating layer. .

Barium sulfate is a radiopharmaceutical that is safe for the human body used for taking pictures of the digestive organs, and has a relatively excellent axon shielding (absorption) effect. However, since barium sulfate has a very high density of 4.5 g / cm 3 and poor compatibility with polyurethane resins, barium sulfate powder is dispersed in polyurethane resin and treated on fabric surface as in the prior art. Poor acidity makes it difficult to form a radiation shielding layer in which barium sulfate is uniformly distributed. Therefore, in order to impart good radiation shielding effect to the fabric by using barium sulfate, more than necessary barium sulfate may be added, thereby placing a great burden on weight and wearability.

In order to overcome the above problems, in the radiation shielding layer 1 of the present invention, a coating layer made of a polyurethane resin is formed on the surface thereof, and an organic iodine-based radiation contrast compound is uniformly dispersed in a powder form inside the coating layer. .

The organic iodine-based radiocontrast compounds include imidotrizoic acid, iooxyglic acid, iophthalamic acid, iotrocitic acid, iotrolic acid, iopanoic acid, iomidol, iohexel, sodium iodate, iodineamide, The well-known organic iodine type compound used as a contrast absorbing agent, such as iodoxamic acid, can be used individually or in mixture of these.

These organic iodine-based radiocontrast compounds absorb radiation and significantly weaken their transmittance. Unlike barium sulfate, the organic iodine-based radiocontrast compounds do not have a large difference in density from polyurethane resins and form hydrogen bonds with polyurethane resins. Very good and safe even in contact with the human body. However, it is preferable to use the mixture with barium sulfate for cost reduction, but the mixing weight ratio (B / A) of barium sulfate (A) and the organic iodine-based radiocontrast compound (B) is 1/1000 to 1/2 It is preferable in view of economical efficiency and uniformity of radiation shielding efficacy.

In this way, when the barium sulfate and the organic iodine-based radiocontrast compound are dispersed in a polyurethane resin and applied to the fabric, a fabric that is harmless to the human body and has good radiation shielding property can be obtained. In addition, in order to further improve the radiation shielding performance of the present invention, alkaline earth metal compounds such as calcium hydroxide, calcium carbonate, magnesium hydroxide, magnesium oxide, magnesium carbonate, bismuth compounds such as bismuth oxycarbonate, or the like may be mixed alone or in combination when forming the coating layer. It may be further added, and an adhesive layer may first be formed on the fabric surface prior to forming the coating layer to form a solid radiation shielding coating layer.

In general, coating processing of fibers has a long history, and processing methods have been developed according to various products. In the present invention, the coating technology developed so far is used, and the target fabric of the coating is nylon, polyester, and the like, and acrylic, vinyl, cotton, rayon, or other blends with other fibers. The coating method and the machine are selected in consideration of the state of the metal, the characteristics of the coating agent, the coating amount, and the like.

The general coating method can be divided into a transfer coating method (Laminate) for attaching a film of resin to the fiber and a direct coating method to form a film by directing the resin on the fabric, the present invention uses a direct coating method, Floating knife method, by installing a knife on the roller to adjust the amount of coating by adjusting the distance between the roller and the knife, a knife on belt method, a reverse roll coating method and the like can be selectively used.

In the neutron shielding layer 2 of the present invention, the thermoplastic polyolefin is a crystalline homopolymer or copolymer obtained by polymerizing ethylene, propylene, 1-butene, 4-methylpentene, 1 hexene, and the like, and polyolefins such as copolymers thereof; Vinyl chloride resin, vinyl acetate resin, polystyrene, fluorine resin, polyamide resin, polyacetal resin, polycarbonate, thermoplastic polyimide, thermoplastic polyurethane, polyphenylene salpide, polyvinyl alcohol, and the like. Among these, polyolefins, such as polyethylene and a polypropylene, are preferable from a moldability and economical viewpoint.

Specifically, the neutron shielding layer 2 of the present invention is prepared by impregnating a solvent in a polyolefin resin in which pores are formed using a blowing agent, and in this case, any solvent can be used as long as it has a neutron shielding ability. Volatile solvents are preferred.

In the molten paraffin, at least one or more elements of gadolinium, boron, and lithium having a particle size of 1 to 10 parts by weight are uniformly dispersed. The metal further increases the neutron shielding ability. When the metal is mixed at less than 1 part by weight, the increase in neutron shielding ability is insufficient, and when it is mixed at 10 parts by weight or more, it is difficult to obtain a uniform dispersion capacity. The size of the metal particles should be less than the nano-size to be evenly dispersed in paraffin in the pores. Specific examples of the metal particles are described below.

As the blowing agent, a decomposition type is used. Specific examples thereof include azodicarbonamide, azodicarboxylic acid metal salt, dinitrosopentamethylenetetramine, hydrazodicarbonamide, p-toluene sulfonyl semicarbazide, s-trihydrazinotriazine, and the like. have.

The addition amount of these blowing agents is about 0.1-10 weight part with respect to 100 weight part of thermoplastic resins normally. In addition, in order to adjust the decomposition behavior of the blowing agent, a foaming aid or a crosslinking aid for adjusting the bubble size can be appropriately added. The addition amount of the said foaming aid and crosslinking adjuvant is about 0.5-50 weight part with respect to 100 weight part of thermoplastic resins normally.

By adding a blowing agent to the thermoplastic resin to form bubbles, in addition to the method of extruding the die temperature above the decomposition temperature of the blowing agent, for example, by heating under pressure in a mold to decompose the blowing agent, decompressing and expanding, After molding in the mold, take out, reheat and cause decomposition to cause expansion. In addition, in order to maintain the bubble shape of the thermoplastic foam, it is preferable to crosslink the resin. As a crosslinking method, the method of using chemical crosslinking agents, such as an organic peroxide, and the method of irradiating radiation, such as an electron beam, can be used.

The macro formation of bubbles by the above-described methods can take various forms under the formation method and the molding conditions. Any of the bubbles may be an independent closed type, an open type connected to each other, or a mixed type thereof. Among these, a close type is preferable.

In addition, although the boundary of foam | bubble may be any of surface shape, columnar shape, or fiber shape, a surface shape is especially preferable. As the microstructure constituting the boundary of the bubble, any one of the polymer lamellar crystals or the laminate thereof is grown in one dimension in a fibrous or columnar shape, in two-dimensional growth in a planar shape, or in three-dimensional growth in a spherical shape. It may be made.

It is preferable that the porosity of the gel-like sheet after foaming is 30 to 90%. If the porosity is less than 30%, the radiation shielding effect is inferior. If the porosity is 90% or more, the durability of the sheet is deteriorated.

In the present invention, it is necessary to break the bubble boundary of the bubble. The foam boundary itself plastically deforms by applying a tensile stress exceeding an internal bubble shape deformation or a compressive stress and then applying a tensile stress to the foam. Specifically, the film is drawn after stretching or stretching. Stretching is performed at a predetermined magnification by the usual tenter method, roll method, inflation method, rolling method, or a combination of these methods.

The bubble boundary is broken as described above, the sheet having the network pore structure is impregnated in the molten paraffin, and interposed between the impermeable polyolefin resin layer 3, and the adhesion of the sheet and the impermeable resin layer uses a conventional bonding method. The sheet sealed with the impermeable resin layer 3 is cooled to below the melting point (47-65 ° C.) of the paraffin to solidify the paraffin to prepare a neutron shielding layer.

Hereinafter, the present invention will be described using specific examples.

<Example>

(1) radiation shielding layer

First, 100 parts by weight of the two-component polyurethane resin, 40 parts by weight of methyl ethyl ketone, 20 parts by weight of toluene, 5 parts by weight of the crosslinking agent and 5 parts by weight of the acrylic resin are uniformly mixed, and then the poly is removed using a floating knife (thickness 1.5 mm). The surface of the ester fabric was applied in an amount of 50 g / m 2 and dried at 130 ° C. for 60 seconds to form an adhesive layer. Subsequently, 100 parts by weight of the one-component polyurethane resin, 200 parts by weight of barium sulfate, 50 parts by weight of imidotrizoic acid, 40 parts by weight of methyl ethyl ketone, and 20 parts by weight of toluene were mixed uniformly, and then a floating knife (thickness) was formed on the formed adhesive layer. 2.0 mm) was applied in an amount of 30 g / ㎡ and dried for 60 seconds at 130 ℃ to prepare a fabric with a radiation shielding layer.

(2) neutron shielding layer

High Density Polyethylene (HDPE) Density 0.955g / cm ³ , Melt Index (MI, 190 ° C, 2.16Kg Load) 9g / 10min 90 parts by weight with Polybutene-1 (PB-1) (M8340, Mitsui Sekiyu Chemical Industries Azodicarbonamide (Aiwa Kagaku Co., Ltd.) as a foaming agent with respect to 100 weight part of resin components which mix | blended 10g weight part of 4 g / 10min (O) Ltd. melt index (MI, 190 degreeC, 2.16Kg load) 5 parts by weight, 1.0 part by weight of trimethol propane trimethacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.) and 1.0 part by weight of an antioxidant as a crosslinking aid; After mixing for 2 minutes at 500 rpm, it was fed to an extruder having a T die of 50 mm phi, length / diameter (L / D) = 28, extruded at an extrusion temperature of 150 ° C., and a sheet having a thickness of 1 mm was prepared.

Next, the sheet was irradiated with an electron beam of 750 KV at a dose of 8 Mrad and crosslinked. Thereafter, the foaming agent was decomposed in a 250 ° C. air oven for 1.0 minute and foamed about 5 times. The apparent density after foaming was 0.19 g / cm ² .

As a result of observing the cross section of this sheet with a scanning electron microscope, it turned out that the foam which the polymer composition comprises a bubble boundary is formed. In addition, as a result of observing a very thinly sliced piece of this sample wrapped with an epoxy resin with a transmission electron microscope, it was found that the microstructure of the bubble boundary consisted of a spherical crystal. This pore size was 28.2 μm and the space ratio was 80.1%.

Next, the sheet was stretched 3 × 3 times to break the bubble boundary to form a sheet having a thickness of 1.8 mm to 5 mm. The bubble boundary is broken on the pressure reducing conveyor belt to inject molten paraffin containing 5 parts by weight of lithium nanoparticles into a sheet having a network structure to prepare a sheet impregnated with oil, and then an impermeable polyethylene resin layer on a cooling roll at 20 ° C. ( After sealing through 1), the neutron shielding layer 2 of the form which paraffin was solidified was manufactured.

The impermeable polyethylene resin was used in thicknesses from 0.2 mm to 10 mm. The impermeable resin is for preventing leakage of oil or the like from the neutron shielding layer.

In this case, the impermeable resin may include at least one element of polyolefin resin or gadolinium, boron, lithium having an average particle size of less than 10 μm, in particular less than 5 μm in diameter. Substances containing the above elements include gadolinium oxide Gd ₂ O ₃ , gadolinium gallium and garnet Gd ₃ Ga ₅ O ₁₂ , gadolinium ferrite GdFeO ₃ , Gd ₃ Fe ₅ O ₁₂ , gadolinium hydroxide Gd (OH) ₃ , and cerium Activated gadolinium silicate Gd ₂ SiO ₅ : Ce, europium activated borate Gadolinium GdBO ₃ : Eu, europium activated gadolinium oxide Gd ₂ O ₃ : Eu, europium activated gadolinium sulfate Gd ₂ O ₂ S : Eu, europium-activated gadolinium Gd ₃ Al ₅ O ₁₂ : Eu, europium-activated gallium acid gadolinium Gd ₃ Ga ₅ O ₁₂ : Eu, europium-activated vanadium acid gadolinium GdVO ₄ : Eu And gallium gadolinium Gd ₃ Ga ₅ O ₁₂ : Ce, Cr, terbium-activated gadolinium oxide Gd ₂ O ₃ : Tb, terbium-activated gadolinium sulfate Gd ₂ O ₂ S: Tb, Gadolinium Sulfate Gd ₂ O ₂ S Activated with Furaseom: Pr, terbium-activated gallium gadolinium Gd ₃ Ga ₅ O ₁₂ : Tb, terbium-activated gadolinium Gd ₃ Al ₅ O ₁₂ : Tb, boron carbide B ₄ C, boron nitride BN, boron phosphide BP, boron sulfide B ₂ S ₃ , boron phosphate BPO ₄ , boron oxide B ₂ O ₃ , lithium oxide Li ₂ O, lithium peroxide Li ₂ O ₂ , lithium aluminate LiAlO ₂ , lithium metaborate LiBO ₂ , lithium tetraborate Li ₂ B ₄ O ₇ , Lithium germanium Li ₂ GeO ₃ , lithium molybdate Li ₂ MoO ₄ , lithium niobate LiNbO ₃ , lithium metasilicate Li ₂ SiO ₃ , lithium titanate LiTaO ₃ , lithium titanate Li ₂ TiO ₃ , lithium vanadate LiVO ₃ , lithium tungstate LiWO ₄ , lithium zirconate Li ₂ ZrO ₃ , lithium nitride Li ₃ N, lithium hydroxide LiOH.H ₂ O, methoxy lithium LiOCH ₃ .

The neutron shielding layer 2 and the impermeable resin layer 3 were laminated between the prepared radiation shielding layers 1 to prepare a fiber for radiation shielding.

The prepared fiber was subjected to radiation shielding experiments in the laboratory. The fiber was cut into 50 × 50 cm, and then the radiation shielding rate was measured 10 times each time according to the source and the average energy shown in Table 1 below, and then the average value and the variation range are shown in Table 1.

% Change = Maximum radiation shielding rate measured-Minimum radiation shielding rate measured

TABLE 1

Radiation class sailor Average energy Shielding rate Change Alpha Line Po-210 5,300 keV 100% 0% beta rays Sr-90 69keV 99% One% Ti-204 72.4keV 100% 0% Gamma rays Am-241 60keV 98% 2% Co-57 122keV 96% 4% X-ray Braking radiation 40 kV 100% 0% 60 kV 100% 0% 80 kV 96% 4% 100 kV 95% 5% 120 kV 93% 7%

<Eutron Shielding Capability Evaluation>

Table 2 below shows the results of the shielding performance of the radiation shielding fibers prepared according to the present invention. A neutron beam outlet of a certain size was made, and a detector capable of measuring the intensity of the neutron was placed at a constant distance (5 cm) from the outlet, and the intensity of the neutron penetrating the fiber was measured. At this time, the thickness of the fiber was measured with a detector. The measured intensities were calculated as neutron absorption cross-sectional coefficients.

The method of calculating the neutron absorption cross section coefficient is as follows.

I / I ₀ = L ^-μx or μ = [log (I ₀ / I)] / x

(I ₀ : incident beam, I: transmission beam, x: transmission thickness, μ: suction area coefficient)

Table 2: Test Results

Thickness (cm) count μ (cm ^-1 ) 0.3 26,735 8.113 0.4 14,023 7,873 0.5 8,356 7.689 0.7 2,753 7.486 0.9 1,132 7.225 1.5 514 6.725 2.0 399 5.742 2.5 336 4.988

As a result of the test, the present invention seems to increase the shielding effect by attenuating energy by scattering radiation in paraffin in the pores of the radiation shielding material having uniform pores in addition to the shielding effect by the metal powder in the resin. In addition, the shielding effect was further increased by the metal powder dispersed in paraffin in the voids. In addition, the shielding effect against the neutron shielding ability as well as other radiation was increased by the radiation shielding layer.

1 is a cross-sectional view for explaining the structure of the radiation shielding material of the present invention.

Figure 2 is a cross-sectional view for explaining the pore structure of the radiation shielding material of the present invention.

* Explanation of reference marks *

A: pore B: polyolefin resin layer

Claims (2)

A first radiation shielding layer 1; The first impermeable resin layer 3; Neutron shielding layer 2; Second impermeable resin layer 3; And It consists of the 2nd radiation shielding layer 1, The first and second radiation shielding layer is formed with a coating layer made of a polyurethane resin on the surface of the fabric, the barium sulfate and organic iodine-based radiocontrast compound is uniformly dispersed in powder form inside the coating layer, The first and second impermeable resin layers are composed of a polyolefin resin or a polyolefin resin containing an inorganic material, The neutron shielding layer is mixed with 0.1 to 10 parts by weight of a blowing agent, 0.5 to 50 parts by weight of a foaming aid and a crosslinking aid with respect to 100 parts by weight of a thermoplastic polyolefin, and foamed after extrusion to prepare a sheet, and the sheet is stretched to form network pores. After the impregnation / cooling in the molten paraffin and sealing between the impermeable resin layer, the molten paraffin is 100 parts by weight of at least one element of gadolinium, boron, lithium having a nanoparticle size of 1 to 10 parts by weight Dispersed in the molten paraffin, the sheet is a radiation shielding material, characterized in that the porosity 30 to 90%. The radiation shielding material according to claim 1, wherein the impermeable resin layer is a polyolefin resin containing at least one element of gadolinium, boron and lithium having an average particle size of less than 10 µm in diameter.

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